An apparatus for controlling an electrohydraulic system of a work machine having an engine that drives a variable displacement pump is disclosed. A pump displacement setting device produces a pump command signal indicative of a desired displacement of the variable displacement pump. An engine speed setting device produces an engine command signal indicative of a desired rotational speed of the engine. A power manager receives the pump and engine command signals, determines an efficient engine speed and pump displacement, and produces an engine control signal that decreases the engine speed to the efficient engine speed and a pump control signal that increases the pump displacement to an efficient pump displacement, while maintaining a substantially constant pump flow rate.